[Comparative effects of dopamine and dobutaine in subendocardial perfusion in the acute phase of myocardial infarct].

Dobutamine, a selective agonist of beta I adrenergic receptors was proposed as an inotropic support of the failing left ventricle in the acute phase of myocardial infarction. We studied the action of Dobutamine (10 micrograms/kg/min) on subendocardial perfusion, compared to the effects of an equipotent dose of Dopamine, in 10 patients with acute transmural infarction. Subendocardial perfusion was assessed by subendocardial viability ratio (EVR), ratio of the diastolic pressure-time index to the systolic pressure-time index. A mean 35 p. cent increase in cardiac index was observed with 10 micrograms/kg/min Dopamine, and with 6,75 micrograms/kg/min Dobutamine; heart rate increased by 13 p. cent with both drugs; with Dobutamine, systolic arterial pressure increased by 9,6 p. cent while pulmonary wedge pressure decreased by 34 p. cent; Dopamine increased systolic arterial pressure by 19 p. cent while pulmonary wedge pressure remained unchanged. Subendocardial viability ratio decreased by 25 p. cent with Dopamine (p less than 0,01) but only by 14 p. cent with Dobutamine (p less than 0,01). Thus, there was significantly less impairment of subendocardial perfusion with Dobutamine and its use is preferable when inotropic support of the failing left ventricle is necessary in the acute stage of myocardial infarction.